Vibratory motor



.ug- 5, 1941. R.v s. PREscoT-r 2,251,419

VIBRATORY MOTOR Filed March 9, 1939 24 l /5 ATToR EY Patented Aug. 5, 1941 'tobert S. Prescott, Brookline, Mass., Gillette Safety Razor Company,

assigner to Boston, Mass.,

a corporation of Delaware Application March S, 1939, Serial No. 269,787

(Cl. HiB- 126) 8 Claims.

The present invention relates to vibratory motors of the type including a forked or U-shaped member having exible magnetic arms and an electro-magnet arranged to be energized in a cycle corresponding substantially to the natural frequency of the arms so that they are maintained in vibration with the expenditure of minimum energy. In one aspect the invention consists in an improved motor of this type having certain novel characteristics which particularly adapt it for use in dry shaving implements or other compact installations where economy of space is an important consideration.

As herein shown the motor of my invention is embodied in a dry shaver having a movable cutter at one end which it is desired to vibrate transversely and in substantially symmetrical relation to the longitudinal axis or center line of the implement. For economy of space and in order to coliform to the general contour of the dry shaver it is desirable to locate the electro-magnetic core of the motor in the longitudinal Center line ol the implement. If the U-shaped vibratory member of the motor is symmetrically located in the implement and With respect to its other elements it is not practical to provide a satisfactory operating connection between the said member and the oscillatory cutter at the center of the cutter, and when the operating connection is moved away from the center an objectionable component of movement at an angle to the path oi the cutter is introduced. If an oiset arm is employed its path of movement is inclined With respect to the path of the cutter so that the full amplitude of movement is not transmitted to the cutter.

All these objections are overcome in accordance with the present invention by mounting the U- shaped vibratory member in oiiset relation to the core of the motor so that one of its arms, or a portion of one of its arms, is located approximately in the center line of the implement, thus supplying a movable actuator from which motion may be derived and transmitted directly to the center of the cutter. As herein shown the U- shaped member is mounted with its bend toward the cutter and with its side arms embracing the electro-magnetic core of the motor. Accordingly, the axis of vibration of each arm is disposed much nearer to the cutter than to the core of the motor and a favorable leverage condition is realized. For example, the distance from the axis of the vibrating arm to the center of effort of the core of the motor may be tWo or three times the distance from the axis to the point of connection with the cutter. In securing the desired results one arm oi the vibrating member is made with a pronounced lateral offset, whereas, the other arm extends substantially straight except for an inward bend at its free end. This characteristic is an important feature of the motor of my invention and contributes to its utility in the dry shaver eld.

These and other features of the invention will be beet understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawing, in which:

Fig. i is a View in elevation of the dry shaver with the motor installed therein, a portion 0f the casing being removed to disclose the motor structure.

FigA 2 and 3 is a View in cross section on the line 3 3 of Fig. l.

The shaving implement herein selected for purposes oi illustration. is provided with a two-piece casing ii) of Bakelite or other moulded material and is shaped to enclose the motor and constitute a handle for the implement. At its upper end, as shown in Figs. l and 2, the casing i0 is provided with a transverse channel ll in which is removably received the stationary head l2 having a series of shearing teeth formed therein. An elongated movable cutter I3 having `co-operating shearing teeth is arranged to reciprocate within the head l 2 and the cutter is actuated by an operating pin ifi to be referred to hereinafter. The shape and design of the head and cutter are of secondary importance only in the present invention.

The casing It is provided with a longitudinally disposed internal web Iii to which is secured an electro-magnetic core i6 of transversely disposed laminations provided with enclosing windings i1. The body of the core is rectangular with rounded corners, or oval, in shape and is secured by riveted feet 2li to the web l5 in symmetrical relation and with its major axis in the center line of the shaving implement. Its side edges are channelled to receive portions of oppositely disposed arms 2l is a corresponding View in side elevation;

and 2li which are arranged to vibrate on opposite sides of the core. When at rest the arms iii-22 stand slightly outside the contour of the core, as shown in Figs. 1 and 3, and when the core is energized they are drawn inwardly.

Secured to the upper end of the web by means of screws it is an elongated metal block I8 having a curved upper end. A U-shaped vibratory member 2t is rigidly secured at its center to the curved end of the block i8 by means of screws 25. The member 25 is narrow as compared to the width of the core i6 and is firmly secured to the web l5 in laterally offset relation to the core, that is to say, the longitudinal axis of the U- shaped member is displaced toward the right a substantial distance with respect to the longitudinal axis of the core and to such an extent that the entire body of the member 20 lies to the right of the center line of the core and the axis of symmetry of the dry shaver,

The arms 2l and 22 are of steel or other ferromagnetic material and are firmly secured to the respective branches or limbs of the U-shaped member 2G. The right-hand arm 2l is substantially straight except that it is bent inwardly and thickened at its free lower end. The end portion 23 of the left-hand arm 22 is attached to the left-hand limb of the U-shaped member 20 and this arm includes a lateral or transverse bend swinging away from the end portion 23; that is, instead of being straight like the arm 20, the arm 22 has a pronounced offset therein. The operating pin i4 projects upwardly from the end portion 23 of the offset arm, being thus located approximately in the center line of the dry shaver and being connected to the cutter i3 at a point halfway between its ends. When the vibratory member is set in motion the upper end s of the pin Ill, therefore, oscillates in a substantially flat arc about a center directly beneath it and located substantially at the point of tangency between the bend and the straight limb l of the U-shaped member 28, Accordingly, prac- I tically the entire movement of the operating pin I4 is transmitted directly to the cutter i3 without wasteful component.

It will be noted moreover that a mechanical advantage and a favorable lever condition is .f

derived from the construction above set forth in that the distance from the axis or center of oscillation of the arm 22 and 23 to the center of eifort of the core is substantially twice the distance from the axis to the upper end of the operating pin lli.

If the implement is intended to operate upon a sixty-cycle circuit the vibrating member 2D will be shaped and proportioned so that its natural frequency is approximately 120 complete oscillations per second. A sixty-cycle alternating current flowing in the windings i1 and inducing 120 attractive impulses per second will, therefore, maintain the two branches of the vibrating member 20 and the arms 2l and 22 in vibration with optimum amplitude and with a minimum input of energy. The cutter i3 is accordingly oscillated at the same rate of vibration by the operating pin ifi acting at its axis of symmetry and with a mechanical leverage advantage as already pointed out. t will be noted that the free ends of the arms 2l and 22 are herein shown as somewhat thickened in order to increase their mass and in this way to take advantage of the greater energy developed for carrying the implement through its cutting cycle.

Having thus disclosed my invention and described a preferred embodiment thereof for illustrative purposes, but not in any limiting sense, I claim as new and desire to secure by Letters Patent:

1. A vibratory motor having an elongated electro-magnetic core with windings thereon, a resilient U-shaped member narrower than the core, carrying armature arms disposed adjacent to opposite sides of said core and arranged to vibrate toward and from it, the bend of the U- shaped member being offset laterally with respect to the longitudinal axis of said core and one branch of said member being located substantially in line with the axis of said core, and an operating arm attached to one side of the bend and projecting away from the core.

2. A vibratory motor having an electro-magnetic core of symmetrical shape with windings thereon, a resilient U-shaped member mounted at one side of the core and oifset laterally with respect to its axis of symmetry with one leg of the U-shaped member disposed substantially in line with said axis, metallic arms secured to said U-shaped member and arranged to vibrate on opposite sides of the core, one of said arms being offset to bring its secured end substantially into line with said axis, and an operating member projecting from said offset arm.

3. A vibratory motor having a single elongated electro-magnetic core, a resilient U-shaped member secured at its bend in laterally offset relation to the axis of symmetry of said core and with both sides free to vibrate and with one side located substantially in line with said axis and having a metallic arm attached to the said side and disposed with its secured end approximately in line with the axis of symmetry of the core, and an operating member projecting from said arm adjacent to the bend of the U-shaped member.

4. In a dry shaver having a head containing a reciprocatory cutter, the combination with an electro-magnetic core of symmetrical contour located in fixed position, of a resilient U-shaped member secured at its bend in a position between the cutter and said core with one branch located substantially in line with the major axis of the iii) core and carrying an armature arm having a part thereof located approximately in the same line, and an operating member for the cutter projecting from said arm in a direction away from the core.

5. In a dry shaver having a head with an oscillatory cutter therein, the combination of an electro-magnetic core of symmetrical outline located in fixed position, with a U-shaped vibratory member mounted with the concave side of its bend facing toward said core and with both branches located on the same side of the axis of the core and carrying armature arms disposed on opposite sides of the core and spaced freely from each other beyond said core, one of said armature arms carrying an operating projection which lies approximately in line with the axis of the core and constitutes the short arm of a lever movable about a fulcrum point adjacent to the bend of the U-shaped member'.

6. In a dry shaver having a head with a reciprocatory cutter therein, the combination of an electro-magnetic core of substantially rectangular outline disposed in iixed position, with a U-shaped vibratory member located at one side of the axis of the core with its side branches carrying armature arms disposed on opposite sides of the core and spaced from each other at their free ends, and a cutter-operating arm carried by one branch of said U-shaped member and extending beyond the convex side of its bend.

'7. A vibratory motor comprising an electromagnetic core mounted in xed position and having metallic armature arms disposed on opposite sides thereof, and a U-shaped vibratory member side of its bend facing said core and with both branches free to vibrate and located on the same side of the axis of the core, armature arms carried by the branches of said U-shaped member and disposed with clearance on opposite sides of the core for movement toward and from the core, and an operating arm attached to one branch of said U-shaped member and extending outwardly past the convex side of its bend`.

ROBERT S. PRESCOTT. 

